Drafting-compasses.



c. H. GRUEE.

DRAFTING COMPASSES.

APPLICATION FILED DEC H. I916.

Patented Sept. 24,1918.

cc. FNOm-LITHO., WASHINGIDN, at a GAB-I: H. GRUBE, OF SGHENEGTADY, NEW YORK.

DRAFTING-COMPASSES.

Specification of Letters Patent. Patented Sept. 24, 1918.

Application filed. December 11, 1916. Serial No. 136,124.

To all whom it may concern:

Be it known that I, CARL H. QRUBE, a citizen of the German Empire, residlng at I Schenectady, county of Schenectady, and

State of New York, have invented certain new and useful Improvements in Drafting- Compasses, of which the following is a specification.

Reference may be had to the accompanying drawing, and the reference characters marked thereon, which form a part of this specification. Similar characters refer to similar parts in the several fi ures therein.

The principal object of t e invention is to automatically maintain in parallelism under different conditions of adjustment, the outer members of the jointed legs of a drafting compass, or the like.

Another object of the invention is to automatically maintain under different conditions of adjutment the handle of a compass or instrument with its axis bisecting the angle between the legs of the instrument.

Figure 1 of the drawings is a view in front elevation of a drafting compass embodying my invention.

Fig. 2 is a view in side elevation of the same.

Fig. 3 is a view in front elevation of one of the outer leg-members detached.

Fig. 4. is a view in perspective of one of the nut-members detached.

Referring to the drawings wherein the invention is shown in preferred form, the instrument has a pair of jointed legs flexibly connected at 1 as by a pivotal connection, each leg comprising an inner member, 2, and an outer member, 3. Each outer legmember, 3, is pivotally mounted at 4 upon its respective inner leg-member and as an angularly or laterally projecting arm, 5.

A pair of nuts, 66, are pivotally mounted at 7, upon the res ective inner legmembers, one of said nuts eing right-handthreaded and the other left-hand-threaded.

Each of said nuts has a laterally projecting arm, 8, said arms being connected by links, 9, with the respective angularly projectin arms, 5, on the outer leg-members, 3.

A rlght-and-left-hand-threaded adjusting screw, 10, engages both nuts, 6, serving as a means for contracting or expanding the compass.

As the compass is contracted or expanded by means of the adjusting screw, the legs of the compass change their angular posi-' tion with relation to the respective nuts, 6,. causlng a relative rotative movement of the nuts, 6, upon the inner leg-members, 2, which movement is transmitted through the links, 9, to the respective angular arms, 5, on the outer leg-members, causing a rotative movement of the outer leg-members upon their respective pivots, 4, relatively to the inner leg-members.

, The angle at which the arms, 5 and 8, project, and the proportions of said arms are such as to maintain the outer leg-members, 3, in substantial parallelism throughout the ordinary range of adjustment of the compass.

I have shown one of the outer leg-mem bers, 3, terminating in a simple point or spur, 11, and the other terminating in a pencil-holder, 12, but it will be understood that the outer leg-members may be formed in any known manner and provided with any known marking means adapting them for draftin or scrlbing purposes.

I have s own the instrument provided with a handle, 13, connected ,with the legs of the compass by a pair of links, 14, said links being pivotally connected at one end at 15, with the handle, and pivotally connected at their other end at 16, one with one of the inner leg-members and the other with the other inner leg-member.

The pivots, 16, are equi-distant from the axis of the pivot, 1, of the compass-legs, and the pivots, 15, are in a line parallel with a line passing through the pivots, 16, so that as the compass is expanded or contracted the handle, 13, will be maintained with its axis bisecting the angle between the legs of the compass whatever that angle may be.

' What I claim as new and desire to secure by Letters Patent is:

1. An instrument of the class described having in combination a pair of flexibly connected jointed legs, the outer member of each leg having a laterally offset arm;

an adjusting screw; a pair of screw-engaging members pivotally mounted upon the respective inner leg-members, and each having a laterally oflset arm; and link-connections between the laterally ofi'set arms on said screw-engaging members and the respective laterally ofi'set arms on the outer leg-members.

2. instrument of the class described having in combination a pair of flexibly connected jointed legs the outer member of between the angularly projecting arms on 16 each leg having an angularly projecting the outer leg memhers and the respective arm; a right-hand-threaded nut pivotally laterally projecting arms on said nuts. mounted on one of the inner leg-members, In testimony whereof I have hereunto set a left-hand-threaded nut pivotally mountedmy hand this ninth day of December, 1916.

upon theother inner leg:member;;-an arm. CARL H. GRUBE; projecting laterally from each of said nuts; WVitnesses:

a right-and-leftdiand-threaded screw en- GEORGE' Hi SMITH,

gagingthe respective nuts; and connections ERNST C. VERWIEBE.

copies 'of -this patent may be obtalined fol 'five cents each; bygaddressiiigthe:Gonimissioner of Patents,

Washihgtonjh' m 

